Multimodal optical spectroscopy for application in the life sciences

Many optical modalities are being investigated, applied, and further developed for non-invasive analysis and sensing in the life sciences. Often, the combination of two or more modalities is required for in depth analysis because of the complexity of the study objects and questions in this field. The work presents multimodal sensing concepts for applications ranging from non-invasive quantification of biomolecules in the living organism to supporting medical diagnosis showing the combined capabilities of Raman spectroscopy, optical coherence tomography, and optoacoustic

Detection, numerical simulation and approximate inversion of optoacoustic signals generated in multi-layered PVA hydrogel based tissue phantoms

In this article we characterize optoacoustic signals generated from layered tissue phantoms via short laser pulses by experimental and numerical means. In particular, we consider the case where scattering is effectively negligible and the absorbed energy density follows Beer-Lambert's law, i.e. is characterized by an exponential decay within the layers and discontinuities at interfaces. We complement experiments on samples with multiple layers, where the material properties are known a priori, with numerical calculations for a pointlike detector, tailored to suit our experimental setup. Experimentally, we characterize the acoustic signal observed by a piezoelectric detector in the acoustic far-field in backward mode and we discuss the implication of acoustic diffraction on our measurements. We further attempt an inversion of an OA signal in the far-field approximation.Comment: 10 pages, 6 figures, supplementary code at https://github.com/omelchert/SONOS.gi

A computational model for previtamin D 3 production in skin

Low levels of vitamin D have been implicated in a wide variety of health issues from calcemic diseases to cancer, diabetes and cardiovascular disease. For most humans, the majority of vitamin D 3 is derived from sunlight. How much vitamin D is produced under given exposure conditions is still widely discussed. We present a computational model for the production of (pre-)vitamin D within the skin. It accounts for spectral irradiance, optical properties of the skin and concentration profile of provitamin D. Results are computed for various sets of these parameters yielding the distribution of produced previtamin D in the skin. © 2012 The Royal Society of Chemistry and Owner Societies

Lighting with laser diodes

Contemporary white light-emitting diodes (LEDs) are much more efficient than compact fluorescent lamps and hence are rapidly capturing the market for general illumination. LEDs are also replacing halogen lamps or even newer xenon based lamps in automotive headlamps. Because laser diodes are inherently much brighter and often more efficient than corresponding LEDs, there is great research interest in developing laser diode based illumination systems. Operating at higher current densities and with smaller form factors, laser diodes may outperform LEDs in the future. This article reviews the possibilities and challenges in the integration of visible laser diodes in future illumination systems. © 2013 Thoss Media & De Gruyter

Statistische Analyse der Arbeitsunfähigkeit in einer deutschen Landarztpraxis

Zur Beschreibung der Arbeitsunfähigkeit (AU) dienten Daten von 490 Patienten einer deutschen Landarztpraxis zwischen 1998 und 2004 mit 2033 AU-Episoden und 15591 AU-Tagen. Resultate: Frauen waren im Durchschnitt länger und häufiger arbeitsunfähig. Eine kleine „Hochnutzergruppe“ (13% der Patienten) wies eine AU-Summe von mehr als 60 Tagen auf und generierte 61,2% der AU-Tage im Kollektiv. In der Hochnutzer-Gruppe fanden sich signifikant häufiger Frauen, Patienten mit psychischen Erkrankungen sowie mit einer AU-Episode von mehr als 15 Tagen in Folge. Die AU-Belastung sank von 1998 - 2003 um 41%. Das Rauchverhalten korrelierte mit der Häufigkeit einer AU durch Atemwegsinfekte. Die Verteilung und Größenordnung der sechs häufigsten AU-Diagnosen im eigenen Kollektiv entsprachen den Daten gesetzlicher Krankenversicherer. Die Merkmale der Hochnutzer-Gruppe indizieren Risikofaktoren einer ungünstigen AU-Entwicklung. Die Bedeutung der AU für die Arzt-Patienten Interaktion wird beleuchtet